At present there are many mechanical and electronic devices different in operation principle and aimed for the formation and recording of graphical images to various carriers. Lead pencil is the most well-known and widely used. Writing lead of the pencil can more or less differ chemically from the graphite, have different color and softness. In most cases the image looks like a wear writing lead on the paper, which is mostly frail and moisture-nonresistant and hence short-lived carrier. Besides, graphite images can be mechanically blurred and effaced.
In every-day use for writing down the graphical information they use pens with one and more writing leads (usually of different colors) possess a rolling writing unit on the tip. These instruments are aimed mostly for writing in paper.
Graphics tablets (pads) for entering graphic information are serially produced and applied. The information is recorded in digital form, but for recording process and its visualization and also for further reading the information from the carrier a program-compatible computer is needed.
Recently a laser electronic pen for entering and writing graphic information has been developed. This device possessing a lead with the ink can write on a usual paper, however, as in the previous case, it is intended for the entering of graphic information mostly in the digital form, so for reading it from the carrier a computer is needed.
Technically closest to the proposed light pen is the light source consisting of a light emitting diode (LED), which generates the radiation in the form of axial and conical components, external collimating optical element in the form of a glass truncated conical lens and the objective in the form of a positive spherical lens mounted with the opportunity of its controllable moving along the optical axis of the device. The light source gives the opportunity to control the size of the light spot in the given plane, however it generates non-polarized radiation of one certain color (depending on LED model), and it is not a completely autonomous device, as for its operation a corresponding power supply is needed, which provides a certain current intensity in the LED. There is a need for a more sophisticated technology for autonomous writing tool that does not require electrical connections.